It's remarkable how someone can make such an impact in his own time, then seem to disappear almost without trace. I was encouraged to read him once, but was not for me. I did not feel it worth my while trying to get my head around him.
I can see this in his story Gulf; however it seems most of Heinlein's writing contains elements of solipsism and I've never been able to connect that with Korzybski, not to say it can't, I wouldn't even want to begin to suggest the two are mutually exclusive--I've just not made a clear connection. That seems to be a much stronger influence than I could make of Korzybski.